ISHS Acta Horticulturae 291: III International Mango Symposium
ENDOGENOUS STEROIDS OF MANGO SHOOT-TIP AND THEIR SIGNIFICANCE IN FLOWERING |
| Authors: | V. Kaushik, S. Ram |
| Abstract:
The radish cotyledon growth test, originally developed for estimation of cytokinins, was standardised for estimation of growth promoting activity of steroids. In this test, steroids such as testosterone, testosterone propionate, androsteronedione, dihydroepiandrosterone, 17 -hydroxyprogesterone and estrone were active at very low concentrations (0.0001 ppm). Out of the fifteen steroid-like factors isolated from emerging mango panicles (designated as L1, L2, L3, L4 (I), L4 (II), L5, L6, L7, L8 (I), L8 (II), L9, L10, L11 (I), L11 (II), and L12) all except L1 and L2 were active in the radish cotyledon growth test and possessed chromogenic reactions specific to steroids. The factors L4 (II), L6, L7, L10, and L11 (I) possessed Rf values and chromogenic reactions similar to that of cortisol, 17-estradiol, cholestrol, testosterone and 5 -androstan - 17 -estradiol-3-one, respectively. The shoot-tip steroids of mango cvs Langra and Baramasia possessed higher growth activity in the first growth flush ('on' year) than that of second growth flush ('off' year) and non-growing (blunt) shoot-tips of Langra from August, 1987 to February, 1988. The peak growth activity in the shoot-tip steroids of first flush of both the cultivars in September and December corresponded with the periods of flower induction and bud break (panicle emergence). No such change in the steroidal activity was observed in the second flush in both the cultivars and also in the blunt shoot-tips of Langra. | |
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